From: nikita <nikita>
Date: Sun, 19 Nov 2006 14:50:21 +0000 (+0000)
Subject: jbd-checkpoint-on-commit: dix possible deadlock.
X-Git-Tag: v1_8_0_110~486^2~127
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=277378e4b616f3d1bc835f0d231c416ac9b09892;p=fs%2Flustre-release.git

jbd-checkpoint-on-commit: dix possible deadlock.
---

diff --git a/lustre/kernel_patches/patches/jbd-checkpoint-on-commit.patch b/lustre/kernel_patches/patches/jbd-checkpoint-on-commit.patch
index 7541cfd..d28272d 100644
--- a/lustre/kernel_patches/patches/jbd-checkpoint-on-commit.patch
+++ b/lustre/kernel_patches/patches/jbd-checkpoint-on-commit.patch
@@ -89,7 +89,7 @@ Index: linux/fs/jbd/journal.c
  		spin_unlock(&journal->j_state_lock);
  		del_timer_sync(journal->j_commit_timer);
  		journal_commit_transaction(journal);
-@@ -168,6 +172,27 @@ loop:
+@@ -168,6 +172,33 @@ loop:
  	}
  
  	wake_up(&journal->j_wait_done_commit);
@@ -100,19 +100,25 @@ Index: linux/fs/jbd/journal.c
 +	 * Do this after wake-up to reduce waiters latency.
 +	 */
 +	spin_unlock(&journal->j_state_lock);
-+	down(&journal->j_checkpoint_sem);
-+	spin_lock(&journal->j_state_lock);
-+	while (__log_space_left(journal) <
-+	       journal->j_max_transaction_buffers + 2 * transaction_size) {
-+		int result;
++	/*
++	 * Trylock to avoid deadlock with threads waiting for commit under
++	 * journal->j_checkpoint_sem.
++	 */
++	if (!down_trylock(&journal->j_checkpoint_sem)) {
++	        spin_lock(&journal->j_state_lock);
++		while (__log_space_left(journal) <
++		       journal->j_max_transaction_buffers +
++		       2 * transaction_size) {
++			int result;
 +
-+		spin_unlock(&journal->j_state_lock);
-+		result = log_do_checkpoint(journal);
-+		spin_lock(&journal->j_state_lock);
-+		if (result < 0)
-+			break;
++			spin_unlock(&journal->j_state_lock);
++			result = log_do_checkpoint(journal);
++			spin_lock(&journal->j_state_lock);
++			if (result < 0)
++				break;
++		}
++		up(&journal->j_checkpoint_sem);
 +	}
-+	up(&journal->j_checkpoint_sem);
 +
  	if (current->flags & PF_FREEZE) {
  		/*